History: Don't flash when swapping documents
History: Don't flash when swapping documents

(i.e., when History is spawned from ReaderUI, delay the flash until we
*show* the next widget, instead of when we close the current RD
instance).

Prevents flashing the InfoMessage.

Frenzie/koreader,poire-z/koreader,poire-z/koreader,koreader/koreader,NiLuJe/koreader,koreader/koreader,Frenzie/koreader,NiLuJe/koreader